In drag chain transport of abrasive material such as cement clinker discharged from a rotary kiln, prior art U.S. Pat. No. 4,886,485 discloses a TAPER-LOC DRAG LINK AND PIN having the ends of the TAPER-LOC PINS adapted for press fit respectively in each of the side arm bosses of the link engaging such ends. The usual pivotal clearance fit is confined to the center barrel element of the link. The TAPER-LOC PIN is provided with a head seated in a counterbore in one of the link side arm bosses; a reduced shoulder for a tight fit in the bore extending through said side arm boss; a further reduced shaft passing through the barrel with a pivotal fit; a further reduced tapered end having a flat face driven into the other side arm boss with a tight fit in a matching tapered boss hole having a matching flat to positively prevent the TAPER-LOC PIN from rotating; and a cross locking pin press fitted into a hole through the tapered pin near that end as a redundant safety feature to positively prevent link pin extraction under any condition.
The tight fit at both ends of the TAPER-LOC PIN and the side arm holes which engage them prevent abrasive grit from entering and the matching flats prevent rotation between the TAPER-LOC PIN and the boss holes in the drag link arms, thereby greatly reducing pin wear which is the principal object of the prior patent. However, the main underface of the chain link which drags abrasive material is also subject to wear which limits the life of the chain in normal use.